Dishwasher Rack Lift Mechanism

ABSTRACT

A rack lifting assembly for a dishwasher appliance is provided. The rack lifting assembly includes a lower rack suspended within the wash chamber by one or more linkage arms. A biasing assembly is configured for rotating the linkage arms to swing the lower rack up and out of the wash chamber. The rack lifting assembly may further include a slide assembly that couples the lower rack to the linkage arms such that the lower rack may extend in the transverse direction.

FIELD OF THE INVENTION

The subject matter of the present disclosure relates generally to adishwasher, and more particularly, to a system for lifting a lower rackof a dishwasher appliance.

BACKGROUND OF THE INVENTION

Dishwasher appliances generally include a tub that defines a washchamber. Rack assemblies can be mounted within the wash chamber of thetub for receipt of articles for washing. Spray assemblies within thewash compartment can apply or direct wash fluid towards articlesdisposed within the rack assemblies in order to clean such articles.Multiple spray assemblies can be provided including e.g., a lower sprayarm assembly mounted to the tub at a bottom of the wash compartment, amid-level spray arm assembly mounted to one of the rack assemblies,and/or an upper spray assembly mounted to the tub at a top of the washcompartment. Other configurations may be used as well.

Typically, the lower rack of a dishwasher is pulled out for loading andunloading of dishes. A dishwasher door pivots into an open, horizontalposition and may define a surface having one or more tracks forreceiving wheels rotatably mounted on the lower rack. The lower rack isrolled out of the tub onto the open dishwasher door to simplify theloading or unloading process, e.g., by not requiring a user to reachinto the wash chamber to add or remove dishes. However, even when therack is extended outside the wash chamber, consumers must often bendover to reach the dishes located in the lower rack, resulting indiscomfort and ergonomic issues. While some dishwashers haveincorporated means for lifting the lower rack, these mechanisms oftenlift the lower rack in a jerky and non-uniform manner. Alternatively,these systems are complex, expensive, and difficult to maintain.

Accordingly, a dishwashing appliance having a system for lifting thelower rack when loading or unloading dishes would be useful. Moreparticularly, a cost effective rack lifting system that may lift thelower rack in a smooth and uniform manner to provide a simple, ergonomicmethod of loading and unloading dishes would be especially beneficial.

BRIEF DESCRIPTION OF THE INVENTION

The present invention provides a rack lifting assembly for a dishwasherappliance. The rack lifting assembly includes a lower rack suspendedwithin the wash chamber by one or more linkage arms. A biasing assemblyis configured for rotating the linkage arms to swing the lower rack upand out of the wash chamber. The rack lifting assembly may furtherinclude a slide assembly that couples the lower rack to the linkage armssuch that the lower rack may extend in the transverse direction. In thismanner, the lower rack of a dishwasher appliance may be raised in asmooth and uniform manner to simplify loading or unloading dishes.Additional aspects and advantages of the invention will be set forth inpart in the following description, may be apparent from the description,or may be learned through practice of the invention.

In one exemplary embodiment, a dishwasher appliance is provided. Thedishwasher appliance defines a vertical, a lateral, and a transversedirection. The dishwasher appliance includes a wash tub that defines awash chamber, a fluid circulation assembly for providing a fluid flowfor cleaning articles placed within the wash chamber; and a lower racklifting assembly. The lower rack lifting assembly includes a lower rackconfigured for receipt of the articles for washing; a linkage arm havinga first end and a second end, the first end being rotatably mounted tothe lower rack; and a biasing assembly operably coupled to the secondend of the linkage arm. The biasing assembly is configured for rotatingthe linkage arm about the second end to swing the lower rack up and outof the wash chamber.

In another exemplary embodiment, a rack lifting assembly for adishwasher appliance defining a vertical, a lateral, and a transversedirection is provided. The rack lifting assembly includes a lower rackconfigured for receipt of articles for washing and a slide assemblyslidably coupled to the lower rack to allow the lower rack to extend inthe transverse direction. The rack lifting assembly further includes alinkage arm having a first end and a second end, the first end beingrotatably mounted to the slide assembly. A biasing assembly is operablycoupled to the second end of the linkage arm, the biasing assembly beingconfigured for rotating the linkage arm about the second end to swingthe lower rack up and out of the wash chamber.

These and other features, aspects, and advantages of the presentinvention will become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the invention and, together with the description, serveto explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth in the specification, which makes reference to the appendedfigures.

FIG. 1 provides a front view of a dishwashing appliance according to anexemplary embodiment of the present subject matter.

FIG. 2 provides a side cross sectional view of the exemplary dishwashingappliance of FIG. 1.

FIG. 3 provides a perspective view of a rack lifting assembly accordingto an exemplary embodiment of the present subject matter.

FIG. 4 provides a perspective view of the exemplary rack liftingassembly of FIG. 3, with the lower rack and slide assembly removed forclarity.

FIG. 5 provides a side view of the exemplary rack lifting assembly ofFIG. 3 in a lowered position.

FIG. 6 provides a perspective view of the exemplary rack liftingassembly of FIG. 3 in a raised and extended position.

FIG. 7 provides a side view of the exemplary rack lifting assembly ofFIG. 3 in a raised and extended position.

FIG. 8 provides a close up perspective view of a biasing assembly of theexemplary rack lifting assembly of FIG. 3.

FIG. 9 provides a perspective, cross sectional view of the biasingassembly of the exemplary rack lifting assembly of FIG. 3, taken alongLine 9-9 of FIG. 8.

FIG. 10 provides a close up perspective view of the slide assembly ofthe exemplary rack lifting assembly of FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

Reference now will be made in detail to embodiments of the invention,one or more examples of which are illustrated in the drawings. Eachexample is provided by way of explanation of the invention, notlimitation of the invention. In fact, it will be apparent to thoseskilled in the art that various modifications and variations can be madein the present invention without departing from the scope or spirit ofthe invention. For instance, features illustrated or described as partof one embodiment can be used with another embodiment to yield a stillfurther embodiment. Thus, it is intended that the present inventioncovers such modifications and variations as come within the scope of theappended claims and their equivalents.

As used herein, the term “article” may refer to, but need not be limitedto, dishes, pots, pans, silverware, and other cooking utensils and itemsthat can be cleaned in a dishwashing appliance. The term “wash cycle” isintended to refer to one or more periods of time during the cleaningprocess where a dishwashing appliance operates while containing articlesto be washed and uses a detergent and water, preferably with agitation,to e.g., remove soil particles including food and other undesirableelements from the articles. The term “rinse cycle” is intended to referto one or more periods of time during the cleaning process in which thedishwashing appliance operates to remove residual soil, detergents, andother undesirable elements that were retained by the articles aftercompletion of the wash cycle. The term “drying cycle” is intended torefer to one or more periods of time in which the dishwashing applianceis operated to dry the articles by removing fluids from the washchamber. The term “fluid” refers to a liquid used for washing and/orrinsing the articles and is typically made up of water that may includeadditives such as e.g., detergent or other treatments. The use of theterms “top” and “bottom,” or “upper” and “lower” herein are used forreference only as exemplary embodiments disclosed herein are not limitedto the vertical orientation shown nor to any particular configurationshown; other constructions and orientations may also be used.

FIGS. 1 and 2 depict an exemplary domestic dishwasher 100 that may beconfigured in accordance with aspects of the present disclosure.Dishwasher 100 generally defines a vertical direction V, a lateraldirection L, and a transverse direction T, each of which is mutuallyperpendicular, such that an orthogonal coordinate system is generallydefined. For the particular embodiment of FIGS. 1 and 2, the dishwasher100 includes a cabinet 102 having a tub or inner liner 104 therein thatdefines a wash chamber 106. The tub 104 includes a front opening (notshown) and a door 110 hinged at its bottom 112 for movement between anormally closed vertical position (shown in FIGS. 1 and 2), wherein thewash chamber 106 is sealed shut for washing operation, and a horizontalopen position for loading and unloading of articles from the dishwasher100. Latch 116 is used to lock and unlock door 110 for access to washchamber 106.

Upper guide rails 120 are mounted on tub side walls 124 and accommodateroller-equipped rack assemblies. More specifically, according to theillustrated exemplary embodiment, upper rack assembly 126 is slidablyreceived on upper guide rails 120. As will be discussed in detail below,lower rack 128 is received within a rack lifting assembly 130. Each ofupper rack 126 and lower rack 128 is fabricated into lattice structuresincluding a plurality of elongated members 132 (for clarity ofillustration, not all elongated members making up upper rack 126 andlower rack 128 are shown in FIG. 2). Each rack 126, 128 is adapted formovement between an extended loading position (not shown) in which therack is substantially positioned outside the wash chamber 106, and aretracted position (shown in FIGS. 1 and 2) in which the rack is locatedinside the wash chamber 106. For upper rack 126, this movement isfacilitated by rollers 134. As will be described in more detail below,lower rack 128 may move between the raised and lowered position usingrack lifting assembly 130. A silverware basket (not shown) may beremovably attached to lower rack 128 for placement of silverware,utensils, and the like, that are otherwise too small to be accommodatedby the racks 126, 128.

The dishwasher 100 further includes a lower spray-arm assembly 140 thatis rotatably mounted within a lower region 142 of the wash chamber 106and above a tub sump portion 144 so as to rotate in relatively closeproximity to lower rack 128. A mid-level spray-arm assembly 146 islocated in an upper region of the wash chamber 106 and may be located inclose proximity to upper rack 126. Additionally, an upper spray assembly148 may be located above the upper rack 126.

The lower, mid-level, and upper spray-arm assemblies 140, 146, and 148are part of a fluid circulation assembly 150 for circulating water anddishwasher fluid in the tub 104. The fluid circulation assembly 150 alsoincludes a pump 152 positioned in a machinery compartment 158 locatedbelow the tub sump portion 144 (i.e., bottom wall) of the tub 104, asgenerally recognized in the art. Pump 152 receives fluid from sump 144and provides a flow to the inlet 154 of a diverter 156. Diverter 156 canbe used to selectively place pump 152 in fluid communication with sprayassemblies 140, 146, or 148 by way of various outlet ports (not shown).Other spray assemblies and connection configurations may be used aswell.

Each spray-arm assembly 140, 146 includes an arrangement of dischargeports or orifices for directing washing liquid received from diverter156 onto dishes or other articles located in rack assemblies 126 and128. The arrangement of the discharge ports in spray-arm assemblies 140,146 provides a rotational force by virtue of washing fluid flowingthrough the discharge ports. The resultant rotation of the spray-armassemblies 140, 146 and the operation of spray assembly 148 using fluidfrom diverter 156 provides coverage of dishes and other dishwashercontents with a washing spray. Other configurations of spray assembliesmay be used as well. For example, dishwasher 100 may have additionalspray assemblies for cleaning silverware, for scouring casserole dishes,for spraying pots and pans, for cleaning bottles, etc. One skilled inthe art will appreciate that the embodiments discussed herein are usedfor the purpose of explanation only, and are not limitations of thepresent subject matter.

Each spray assembly may receive an independent stream of fluid, may bestationary, and/or may be configured to rotate in one or bothdirections. For example, a single spray arm may have multiple sets ofdischarge ports, each set receiving wash fluid from a different fluidconduit, and each set being configured to spray in opposite directionsand impart opposite rotational forces on the spray arm. In order toavoid stalling the rotation of such a spray arm, wash fluid is typicallyonly supplied to one of the sets of discharge ports at a time.

The dishwasher 100 is further equipped with a controller 160 to regulateoperation of the dishwasher 100. The controller 160 may include one ormore memory devices and one or more microprocessors, such as general orspecial purpose microprocessors operable to execute programminginstructions or micro-control code associated with a cleaning cycle. Thememory may represent random access memory such as DRAM, or read onlymemory such as ROM or FLASH. In one embodiment, the processor executesprogramming instructions stored in memory. The memory may be a separatecomponent from the processor or may be included onboard within theprocessor.

The controller 160 may be positioned in a variety of locationsthroughout dishwasher 100. In the illustrated embodiment, the controller160 may be located within a control panel area 162 of door 110 as shownin FIGS. 1 and 2. In such an embodiment, input/output (“I/O”) signalsmay be routed between the control system and various operationalcomponents of dishwasher 100 along wiring harnesses that may be routedthrough the bottom 112 of door 110. Typically, the controller 160includes a user interface panel/controls 164 through which a user mayselect various operational features and modes and monitor progress ofthe dishwasher 100. In one embodiment, the user interface 164 mayrepresent a general purpose I/O (“GPIO”) device or functional block. Inone embodiment, the user interface 164 may include input components,such as one or more of a variety of electrical, mechanical orelectro-mechanical input devices including rotary dials, push buttons,and touch pads. The user interface 164 may include a display component,such as a digital or analog display device designed to provideoperational feedback to a user. The user interface 164 may be incommunication with the controller 160 via one or more signal lines orshared communication busses.

It should be appreciated that the invention is not limited to anyparticular style, model, or configuration of dishwasher 100. Theexemplary embodiment depicted in FIGS. 1 and 2 is for illustrativepurposes only. For example, different locations may be provided for userinterface 164, different configurations may be provided for racks 126,128, different spray arm assemblies 140, 146, 148 may be used, and otherdifferences may be applied as well.

Referring now generally to FIGS. 3-10, lower rack lifting assembly 130will be described in more detail. According to the exemplary illustratedembodiment, lower rack 128 has a first side 170 and a second side 172spaced apart along the lateral direction L. Rack lifting assembly 130may include a first linkage system 174 operably coupled with first side170 and a second linkage system 176 operably coupled with second side172 which may suspend lower rack 128 within wash chamber 106. Using racklifting assembly 130, lower rack 128 may be moved between a firstposition where it is lowered and retracted within wash chamber 106 (seeFIG. 2), and a second position where it is raised and/or extended out ofwash chamber 106 (see FIGS. 6 and 7), as described below.

The structure and operation of each linkage system 174, 176 will now bedescribed referring specifically to first linkage system 174. Althoughthe description below refers to first linkage system 174, one skilled inthe art will appreciate that second linkage system 176 may have asimilar construction and operate in a similar manner.

First linkage system 174 includes a first linkage arm 180 having a firstend 182 and a second end 184 and a second linkage arm 186 having a firstend 188 and a second end 190. According to the illustrated embodiment,linkage arms 180, 186 are wider at first ends 182, 188 than at secondends 184, 190. As described in more detail below, second ends 184, 190are rotatably mounted to biasing assembly 220 and wash tub 104,respectively. Wider first ends 182, 188 may be pivotally connected attwo points along the width of linkage arms 180, 186. For example, firstends 182, 188 may be pivotally connected to slide assembly 200 andconnecting arm 240, as described in detail below. According to theillustrated embodiment, the various rotatable connections to linkagearms 180, 188 are made using rigid steel pins. However, according toalternative embodiments, other suitable mounting mechanisms may be used,e.g., bush bearings.

According to the illustrated embodiment, first ends 182, 188 arerotatably attached to a slide assembly. In this regard, rack liftingassembly 130 may include a first slide assembly 200 and a second slideassembly 202 which are mounted on opposing sides of lower rack 128 toallow lower rack 128 to slide in the transverse direction T relative tolinkage arm 180. More particularly, first slide assembly 200 is mountedto first side 170 of lower rack 128 and second slide assembly 202 ismounted to second side 172 of lower rack 128 to allow lower rack 128 toextend away from linkage arms 180, 186.

Each slide assembly 200, 202 may include a guide 204 and one or moreslide members 206 that move linearly relative to guide 204 via asuitable bearing arrangement. In an alternative embodiment, multipleslide members may telescope relative to each other. Slide member 206 maybe mounted to lower rack 128 using a suitable support. Morespecifically, a first support 210 and a second support 212 may bemounted on opposing sides of lower rack 128 and be configured forreceiving drawer slide assemblies 200, 202. In this regard, firstsupport 210 may be mounted to first side 170 and second support 212 maybe mounted to second side 172 of lower rack 128.

Slide assemblies 200, 202 and supports 210, 212 may be constructed fromany suitably rigid material. For example, first support 220 and secondsupport 222 may be constructed from steel. Lower rack 128 may beattached to slide 206 and linkage arms 180, 186 may be attached to guide204 using any suitable mechanical fastener, such as screws, bolts,rivets, etc. Similarly, glue, snap-fit mechanisms, interference-fitmechanisms, or any suitable combination thereof may secure lower rack128 and linkage arms 180, 186 to slide assemblies 200, 202. In addition,linkage arms 180, 186 may be rotatably connected to guide 204 of slideassemblies 200, 202, such that linkage arms 180, 186 rotate, but do notslide, relative to slide assemblies 200, 202. Other attachment means arealso possible.

According to the illustrated embodiment, second end 184 of first linkagearm 180 is operably coupled to a biasing assembly 220. In general,biasing assembly 220 is any mechanism configured for urging firstlinkage arm 180 to rotate about its second end 184. More particularly,biasing assembly 220 urges first linkage arm 180 to rotate in theclockwise direction (as viewed in FIG. 5). In this manner, first linkagearm 180 may swing lower rack 128 up and out of wash chamber 106. Forexample, biasing assembly 220 may be an electric or hydraulic motor thatis mounted to wash tub 104 and is configured to rotate first linkage arm180. Motor may be powered, for example, directly from a power supplythat is internal or external to dishwasher 100.

Alternatively, according to the illustrated exemplary embodiment,biasing assembly 220 includes a support bracket 222 having a geared rack224 slidably mounted thereto. In this regard, support bracket 222 is arigid plate with flanges turned in on either side to form a U-shape andthereby defining a space to receive geared rack 224. Support bracket 222may be attached to wash tub 104 using any suitable means, e.g., bywelding or using mechanical fasteners such as bolts or rivets. Oneskilled in the art will appreciate that other configurations of supportbracket 222 and geared rack 224 are possible. Moreover, according tosome exemplary embodiments, no support bracket 222 may be used andgeared rack 224 and other components of biasing assembly 220 may bemounted directly to wash tub 104.

Geared rack 224 may be configured to slide along a longitudinal axis Aof support bracket 222 (FIG. 5). According to some exemplaryembodiments, geared rack 224 may slide along the base or flange ofsupport bracket 222. Alternatively, geared rack 224 may define a slotthat slides along a pin (not shown) protruding from support bracket 222.According to the illustrated embodiment, a support pin 226 is insteadpositioned underneath geared rack 224 to ensure it slides along adirection corresponding to the longitudinal axis A. Other means forsupporting geared rack 224 are also possible and within the scope of thepresent subject matter.

A pinion gear 230 may be coupled to first linkage arm 180 and rotatablymounted to support bracket 222 such that pinion gear 230 engages gearedrack 224. As best shown in FIG. 9, pinion gear 230 may be fixed to firstlinkage arm 180 and support bracket 222 by a fastener, e.g., bolt 232.Bolt 232 may engage pinion gear 230 and first linkage arm 180 in amanner that ensures that they rotate together. For example, bolt 232 mayhave a shaft with two keyed portions that engage keyed apertures inlinkage arm 180 and pinion gear 230, respectively. In this manner piniongear 230 and first linkage arm 180 may be configured to rotate together.Notably, support pin 226 may be positioned such that geared rack 224remains engaged with pinion gear 230 as it slides along longitudinalaxis A. In this manner, as geared rack 224 moves along the longitudinalaxis A, pinion gear 230 is rotated along with first linkage arm 180.

A biasing member may be configured to urge geared rack 224 to move alongthe longitudinal axis A. According to the illustrated embodiment,biasing member is one or more springs 234. A spring base 236 is fixed tosupport bracket 222 and oriented perpendicular to the longitudinal axisA. A spring bar 238 may be slidably mounted within the support bracket222 and may be attached to geared rack 224. Springs 234 may extend alongthe longitudinal axis A between spring base 236 and spring bar 238.According to the illustrated embodiment, there are four springs 234,however springs of varying size and stiffness may be used depending onthe spring force required.

Springs 234 may be in a compressed state when lower rack 128 ispositioned within wash chamber 106 (as shown in FIG. 2). In this manner,as lower rack 128 is pulled out of wash chamber 106 to its extendedposition, springs 234 urge spring bar 238 along the longitudinal axis A,thereby also urging geared rack 224 to rotate pinion gear 230. In thismanner, first linkage arm 180 rotates in a clockwise direction (as shownin FIG. 5) and assists the user in raising lower rack 128 to the raisedposition. Notably, springs 234 may both urge lower rack 128 into theraised position as well as decelerate lower rack 128 as it moves intothe lowered position. In this manner, springs 234 prevent lower rack 128from slamming into the back wall of wash tub 104 when being pushed bythe user.

Although the exemplary embodiment described the use of springs 234 tourge geared rack 224 in a manner that raises lower rack 128 out of washchamber 106, one skilled in the art will appreciate that other means formoving geared rack 224 may be used. For example, one or more gassprings, hydraulic cylinders, or mechanical actuators may be usedinstead of mechanical springs 234. Other configurations are possible andwithin the scope of the present subject matter.

According to the illustrated exemplary embodiment, biasing assembly 220is angled with respect to the transverse direction T of dishwasher 100.More specifically, the longitudinal axis A of biasing assembly 220 isoriented at an angle, e.g., 15 degrees, relative to the transversedirection T. This may help reduce the force required by springs 234 torotate pinion gear 230 and prevent rack lifting assembly 130 frombinding in wash chamber 106. However, according to alternative exemplaryembodiments, biasing assembly 220 may instead have any other suitableorientation, e.g., its longitudinal axis may be parallel to thetransverse direction T.

According to an exemplary embodiment, first linkage arm 180 is the drivearm that urges lower rack 128 into a raised position. First end 188 ofsecond linkage arm 186 may also be rotatably mounted to slide assembly200 and second end 190 of second linkage arm may be rotatably mounted towash tub 104 or support bracket 222. In addition, a connecting arm 240may be rotatably attached to first end 182 of first linkage arm 180 andfirst end 188 of second linkage arm 186. More particularly, linkage arms180, 186 may be pivotally connected to connecting arm 240 using pinsthat are positioned on wide first ends 182, 188 and below slideassemblies 200, 202. In this manner, the pins that connect linkage arms180, 186 to connecting arm 240 may rotate around the pins that connectlinkage arms 180, 186 to slide assemblies 200, 202. In this manner,linkage arms 180, 186 and connecting arm 240 may form a four bar linkageand provide additional structural support to first linkage system 174.

Although the illustrated embodiment shows first linkage system 174 andsecond linkage system 176 each having a separate biasing assembly 220driving a four bar linkage system, one skilled in the art willappreciate that this is only one exemplary configuration of rack liftingassembly 130. Modifications and variations are possible. For example, asingle linkage arm might be used on each side of lower rack 128 insteadof a four bar linkage system. In addition, a single biasing assembly 220may be used instead of two or biasing assembly 220 may drive secondlinkage arm 186 instead of first linkage arm 180. Such variations andmodifications are considered to be within the scope of the presentdisclosure.

According to the illustrated exemplary embodiment, rack lifting assembly130 may further include a stopper bracket 250 that extends along thelateral direction L and is connected between first linkage system 174and second linkage system 176. More particularly, stopper bracket 250may extend between second linkage arms 186 of first and second linkagesystems 174, 176. Stopper bracket 250 may ensure that linkage systems174, 176 move in unison. In addition, stopper bracket may contact a backwall of wash chamber 106 when lower rack 128 reaches the loweredposition. In this manner, stopper bracket may be configured to preventlower rack 128 from knocking into back wall. According to anotherexemplary embodiment, stopper bracket 250 may have a pad or bumper onits rear surface to absorb any impact of rack lifting assembly 130 andreduce the noise of any such impact.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they include structural elementsthat do not differ from the literal language of the claims or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal language of the claims.

What is claimed is:
 1. A dishwasher appliance defining a vertical, alateral, and a transverse direction, the dishwasher appliancecomprising: a wash tub that defines a wash chamber; a fluid circulationassembly for providing a fluid flow for cleaning articles placed withinthe wash chamber; and a lower rack lifting assembly comprising: a lowerrack configured for receipt of the articles for washing; a linkage armhaving a first end and a second end, the first end being rotatablymounted to the lower rack; and a biasing assembly operably coupled tothe second end of the linkage arm, the biasing assembly being configuredfor rotating the linkage arm about the second end to swing the lowerrack up and out of the wash chamber.
 2. The dishwasher appliance ofclaim 1, wherein the linkage arm is a first linkage arm, the lower racklifting assembly further comprising: a second linkage arm having a firstend and a second end, the first end being rotatably mounted to the lowerrack and the second end being rotatably mounted to the wash tub; and aconnecting arm attached to the first end of the first linkage arm andthe first end of the second linkage arm, thereby forming a four barlinkage system.
 3. The dishwasher appliance of claim 1, wherein thelower rack lifting assembly further comprises a slide assembly, theslide assembly slidably coupling the lower rack to the linkage arm toallow the lower rack to extend in the transverse direction relative tothe linkage arm.
 4. The dishwasher appliance of claim 3, wherein theslide assembly comprises a slide fixed to the lower rack and a guidefixed to the first end of the linkage arm such that the slide may bereceived in the guide.
 5. The dishwasher appliance of claim 1, whereinthe biasing assembly comprises: a support bracket; a geared rackslidably mounted to the support bracket; a pinion gear coupled to thelinkage arm and rotatably mounted to the support bracket such that thepinion gear engages the geared rack; and a biasing member configured tourge the geared rack to slide within the support bracket, therebyrotating the pinion gear and the linkage arm.
 6. The dishwasherappliance of claim 5, wherein the biasing member is one or more springs,wherein the one or more springs are in compression when the lower rackis in a lowered position within the wash chamber.
 7. The dishwasherappliance of claim 5, wherein the biasing assembly defines alongitudinal axis that corresponds to a direction of motion of thegeared rack, the longitudinal axis being inclined relative to thetransverse direction.
 8. The dishwasher appliance of claim 5, whereinthe biasing member is a gas spring or a hydraulic cylinder.
 9. Thedishwasher appliance of claim 1, wherein the biasing assembly comprisesa motor configured for rotating the linkage arm about the second end ofthe linkage arm.
 10. The dishwasher appliance of claim 1, wherein thelower rack lifting assembly is a first rack lifting assembly disposed ata first lateral side of the lower rack, the dishwasher appliance furthercomprising a second rack lifting assembly disposed at a second lateralside of the lower rack.
 11. The dishwasher appliance of claim 10,wherein a stopper bracket extends along the lateral direction and isconnected between the first rack lifting assembly and the second racklifting assembly, the stopper bracket configured for contacting a backwall of the wash chamber when the lower rack is in a lowered position.12. A rack lifting assembly for a dishwasher appliance defining avertical, a lateral, and a transverse direction, the rack liftingassembly comprising: a lower rack configured for receipt of articles forwashing; a slide assembly slidably coupled to the lower rack to allowthe lower rack to extend in the transverse direction; a linkage armhaving a first end and a second end, the first end being rotatablymounted to the slide assembly; and a biasing assembly operably coupledto the second end of the linkage arm, the biasing assembly beingconfigured for rotating the linkage arm about the second end to swingthe lower rack up and out of the wash chamber.
 13. The rack liftingassembly of claim 12, wherein the linkage arm is a first linkage arm,the lower rack lifting assembly further comprising: a second linkage armhaving a first end and a second end, the first end being rotatablymounted to the slide assembly and the second end being rotatably mountedto the wash tub; and a connecting arm attached to the first end of thefirst linkage arm and the first end of the second linkage arm, therebyforming a four bar linkage system.
 14. The rack lifting assembly ofclaim 12, wherein the slide assembly comprises a slide fixed to thelower rack and a guide fixed to the first end of the linkage arm suchthat the slide may be received in the guide.
 15. The rack liftingassembly of claim 12, wherein the biasing assembly comprises: a supportbracket; a geared rack slidably mounted to the support bracket; a piniongear coupled to the linkage arm and rotatably mounted to the supportbracket such that the pinion gear engages the geared rack; and a biasingmember configured to urge the geared rack to slide within the supportbracket, thereby rotating the pinion gear and the linkage arm.
 16. Therack lifting assembly of claim 15, wherein the biasing member is one ormore springs, wherein the one or more springs are in compression whenthe lower rack is in a lowered position within the wash chamber.
 17. Therack lifting assembly of claim 15, wherein the biasing assembly definesa longitudinal axis that corresponds to a direction of motion of thegeared rack, the longitudinal axis being inclined relative to thetransverse direction.
 18. The rack lifting assembly of claim 12, whereinthe biasing assembly comprises a motor configured for rotating thelinkage arm about the second end of the linkage arm.
 19. The racklifting assembly of claim 12, wherein the lower rack lifting assembly isa first rack lifting assembly disposed at a first lateral side of thelower rack, the dishwasher appliance further comprising a second racklifting assembly disposed at a second lateral side of the lower rack.20. The rack lifting assembly of claim 19, wherein a stopper bracketextends along the lateral direction and is connected between the firstrack lifting assembly and the second rack lifting assembly, the stopperbracket configured for contacting a back wall of the wash chamber whenthe lower rack is in a lowered position.